50 Transactions. — Zoology. 



Two points require slight mention here. First, it is to be 

 noted that in many instances, where animalcules have been 

 referred in this paper to described species, there have been 

 observed minute variations, not considered sufficiently important 

 to induce the erection of a new species, yet often tending to make 

 identification a matter of some difficulty. Instances of this 

 may be mentioned in the genera Stentor, EiigJena, and others, and 

 especially, perhaps, in the Heterotrichous Order. It has been 

 considered desirable to avoid as much as possible the multiplica- 

 tion of species. Secondly, it is noticeable that in some instances 

 — e.g., Aspidisca turrita, Licnophora setifera — animalcules inhabit 

 freshwater here which are only reported from sea-water in 

 Europe or elsewhere. 



Finally, it is to be observed that examination has only been 

 made into strictly freshwater animalcules, excluding marine or 

 " infusion" types. The present paper, being only the beginning 

 of what may easily be a long task, has been purposely compli- 

 cated as little as possible. 



Catalogue of Infusoria. 

 Class I. FLAGELLATA. 

 Order. Flagellata-Pantostomata. 

 Genus Monas. 

 Monasjluida, Duj. Wellington. 

 Monas attenuata,'Di\j. Wellington; Wainui. 

 Probably several others of this genus may also occur here. 



Genus Scytomonas. 

 Scytomonas pusilla, 8tein. Wellington. 



Genus Oikomonas. 

 Oikomonas mutabiUs, Kent. Wainui. 



Genus Cercomonas. 

 Cercomonas grandis, sp. nov. Plate III., fig. 1, a, h, c, d, e. 



Animalcules free-swimming, variable in shape, globular or 

 elongate, with a single anterior terminal flagellum, and a some- 

 what shorter posterior terminal filament. Flagellum about 

 half the length of the fully extended body. Contractile vesicle 

 single, central. 



Length when fully extended -ji^ inch = G2yLz. No oral aper- 

 ture. 



Wellington, TV. M. Maskell. 



Differs from described species in its very large size. The 

 presence of a caudal filament and the absence of an oral aper 

 ture remove it from the genus Astasia, 



